scholarly journals The properties of the massive neutron star PSR J0348+0432

2015 ◽  
Vol 24 (08) ◽  
pp. 1550058 ◽  
Author(s):  
Xian-Feng Zhao
Keyword(s):  
Neutron Star ◽  
Energy Density ◽  
Mean Field ◽  
Coupling Constants ◽  
Gravitational Redshift ◽  
Central Pressure ◽  
Relativistic Mean Field ◽  
Massive Neutron Star ◽  
Central Energy ◽  
Well Depth

The properties of the massive neutron star PSR J0348+0432 is calculated in the framework of the relativistic mean field (RMF) theory by choosing the suitable hyperon coupling constants. It is found that the central energy density ϵc and the central pressure pc of the massive neutron star PSR J0348+0432 respectively are 1.5 times larger and 3.6 times larger than those of the canonical mass neutron star. It is also found that in the neutron star PSR J0348+0432 there are five kinds of baryons appearing: n, p, Λ, Ξ- and Ξ0 but in the canonical mass neutron star there are only three kinds of particles appearing: n, p and Λ. In our models, the positive well depth [Formula: see text] will restrict the production of the hyperons Σ-, Σ0 and Σ+ and therefore either in the neutron star PSR J0348+0432 or in the canonical mass neutron star the hyperons Σ-, Σ0 and Σ+ all do not appear. In addition, our results also show that the radius R of the massive neutron star PSR J0348+0432 is less than that of the canonical mass neutron star while the gravitational redshift of the former is larger than that of the latter.

Effect of hyperon coupling constants on the properties of the massive neutron star PSR J0348+0432

2019 ◽  
Vol 28 (11) ◽  
pp. 1950144
Author(s):  
Xian-Feng Zhao
Keyword(s):  
Neutron Star ◽  
Potential Field ◽  
Mean Field ◽  
Particle Number Density ◽  
Coupling Constants ◽  
Repulsive Interaction ◽  
Relativistic Mean Field ◽  
Chemical Potentials ◽  
Massive Neutron Star ◽  
Field Strengths

The relativistic mean field (RMF) theory is used to examine the effect of the meson-[Formula: see text] coupling constants on the properties of the neutron star (NS) PSR J0348+0432 when the hyperon potential of [Formula: see text] is fixed. It is found that the greater the [Formula: see text] and [Formula: see text], the stronger the repulsive interaction. The potential field strengths of mesons [Formula: see text] and [Formula: see text] and the chemical potentials of neutron n and electron e increase, whereas the potential field strengths of mesons [Formula: see text] decrease with the increase of the meson-[Formula: see text] coupling constants. It is also found that the relative particle number density of neutron [Formula: see text] and hyperon [Formula: see text] in the NS PSR J0348+0432 increase, whereas that of hyperon [Formula: see text] decrease as the meson-[Formula: see text] coupling constants increase. In our calculations, hyperon [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] all do not appear. Our results show that the meson-[Formula: see text] coupling constants cannot be uniquely determined as the hyperon-potential of [Formula: see text] is determined. Therefore, the related properties of NS cannot be uniquely determined only by the determined hyperon potential of [Formula: see text].

Effects of trapped neutrinos on the composition and structure of massive protoneutron stars

2017 ◽  
Vol 26 (08) ◽  
pp. 1750077 ◽  
Author(s):  
Xia Zhou ◽  
Huanyu Jia ◽  
Bin Hong ◽  
Xueling Mu ◽  
Hui Wang
Keyword(s):  
Neutron Star ◽  
Mean Field ◽  
Coupling Constants ◽  
Internal Temperature ◽  
Density Region ◽  
Relativistic Mean Field ◽  
Composition And Structure ◽  
Massive Neutron Star ◽  
Number Formula ◽  
Protoneutron Stars

The properties of massive protoneutron stars (PNSs) are of great significance for the study of supernova and the evolution of neutron stars or black holes. The mass of the massive neutron star PSR J1614-2230 is fitted by selecting the nuclear coupling constants and adjusting the hyperon coupling constants in the framework of the relativistic mean field (RMF) theory. The model is then extrapolated to calculate the properties of massive PNS with the trapped neutrinos. The effects of different trapped neutrinos on the composition and structure of massive PNSs are discussed for entropy per baryon [Formula: see text]. Results show that the presence of trapped neutrinos increase the energy density. Moreover, the significant neutrinos trapped, such as electron leptons number [Formula: see text], reduces the pressure of massive PNSs in the density region 0.2–0.5[Formula: see text]fm[Formula: see text], that is to say, the equation-of-state (EOS) is softened in this region. The maximum masses and corresponding radii of massive PNSs are calculated to be 2.110[Formula: see text][Formula: see text], 2.106[Formula: see text][Formula: see text], 2.095[Formula: see text][Formula: see text], 2.082[Formula: see text][Formula: see text] and 12.19, 11.88, 11.75 and 11.81 km for the electron leptons number [Formula: see text]. We calculate the distribution of the internal temperature, and get the effects of the trapped neutrinos on the internal temperature of massive PNSs for the first time. For the different electron leptons number [Formula: see text], the central temperatures of the massive PNS, when the mass is taken to be the same as that of the observed neutron star PSR J1614-2230[Formula: see text], are [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text][Formula: see text]MeV, respectively.

scholarly journals Relativistic density functional for nuclear matter

2019 ◽  
Vol 204 ◽  
pp. 05001
Author(s):  
Stefan Gmuca ◽  
Kristian Petrík ◽  
Jozef Leja
Keyword(s):  
Energy Density ◽  
Nuclear Matter ◽  
Density Functional ◽  
Mean Field ◽  
Dense Matter ◽  
Coupling Constants ◽  
Effective Coupling ◽  
Hartree Fock ◽  
Relativistic Mean Field ◽  
Rmf Model

In the present work, we have mapped the exchange Fock contributions from the Dirac–Hartree–Fock (DHF) approach for nuclear matter onto the direct Hartree terms. This results in the relativistic mean field (RMF) model with the density dependent couplings. The density dependence of the effective coupling constants thus reflects the exchange correlations. The exchange part of an energy density of the linear DHF model in dense matter is evaluated in a parameter-free closed form and, after the rearrangement of the terms, expressed as density functional.

scholarly journals Constraints on Microscopic and Phenomenological Equations of State of Dense Matter from GW170817

Universe ◽  
2019 ◽  
Vol 5 (10) ◽  
pp. 204 ◽  
Author(s):  
Domenico Logoteta ◽  
Ignazio Bombaci
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Equations Of State ◽  
Mean Field ◽  
Dense Matter ◽  
Neutron Star Matter ◽  
Field Approach ◽  
Relativistic Mean Field ◽  
Three Body ◽  
Good Agreement

We discuss the constraints on the equation of state (EOS) of neutron star matter obtained by the data analysis of the neutron star-neutron star merger in the event GW170807. To this scope, we consider two recent microscopic EOS models computed starting from two-body and three-body nuclear interactions derived using chiral perturbation theory. For comparison, we also use three representative phenomenological EOS models derived within the relativistic mean field approach. For each model, we determine the β -stable EOS and then the corresponding neutron star structure by solving the equations of hydrostatic equilibrium in general relativity. In addition, we calculate the tidal deformability parameters for the two neutron stars and discuss the results of our calculations in connection with the constraints obtained from the gravitational wave signal in GW170817. We find that the tidal deformabilities and radii for the binary’s component neutron stars in GW170817, calculated using a recent microscopic EOS model proposed by the present authors, are in very good agreement with those derived by gravitational waves data.

scholarly journals Effects of symmetry energy on the radius and tidal deformability of neutron stars in the relativistic mean-field model

2020 ◽  
Vol 2020 (4) ◽  
Author(s):  
Jinniu Hu ◽  
Shishao Bao ◽  
Ying Zhang ◽  
Ken’ichiro Nakazato ◽  
Kohsuke Sumiyoshi ◽  
...  
Keyword(s):  
Neutron Stars ◽  
Symmetry Energy ◽  
Binary Star ◽  
Mean Field ◽  
Mass Region ◽  
Saturation Density ◽  
Coupling Constants ◽  
Mean Field Model ◽  
Relativistic Mean Field ◽  
The Family

Abstract The radii and tidal deformabilities of neutron stars are investigated in the framework of the relativistic mean-field (RMF) model with different density-dependent behaviors of symmetry energy. To study the effects of symmetry energy on the properties of neutron stars, $\omega$ meson and $\rho$ meson coupling terms are included in a popular RMF Lagrangian, i.e., the TM1 parameter set, which is adopted for the widely used supernova equation of state (EoS) table. The coupling constants relevant to the vector–isovector meson, $\rho$, are refitted by a fixed symmetry energy at subsaturation density and its slope at saturation density, while other coupling constants remain the same as the original ones in TM1 so as to update the supernova EoS table. The radius and mass of maximum neutron stars are not so sensitive to the symmetry energy in these family TM1 parameterizations. However, the radii in the intermediate-mass region are strongly correlated with the slope of symmetry energy. Furthermore, the dimensionless tidal deformabilities of neutron stars are also calculated within the associated Love number, which is related to the quadrupole deformation of the star in a static external tidal field and can be extracted from the observation of a gravitational wave generated by a binary star merger. We find that its value at $1.4 \mathrm{M}_\odot$ has a linear correlation to the slope of symmetry energy, unlike that previously studied. With the latest constraints of tidal deformabilities from the GW170817 event, the slope of symmetry energy at nuclear saturation density should be smaller than $60$ MeV in the family TM1 parameterizations. This fact supports the usage of a lower symmetry energy slope for the updated supernova EoS, which is applicable to simulations of neutron star mergers. Furthermore, an analogous analysis is also done within the family IUFSU parameter sets. It is found that the correlations between the symmetry energy slope with the radius and tidal deformability at $1.4 \mathrm{M}_\odot$ have very similar linear relations in these RMF models.

DELTA MATTER FORMATION IN DENSE ASYMMETRIC NUCLEAR MEDIUM

2000 ◽  
Vol 15 (24) ◽  
pp. 1529-1537 ◽  
Author(s):  
J. C. T. DE OLIVEIRA ◽  
M. KYOTOKU ◽  
M. CHIAPPARINI ◽  
H. RODRIGUES ◽  
S. B. DUARTE
Keyword(s):  
Nuclear Matter ◽  
Mean Field Theory ◽  
Mean Field ◽  
Symmetric Nuclear Matter ◽  
Coupling Constants ◽  
Nuclear Medium ◽  
Delta Resonance ◽  
Relativistic Mean Field ◽  
Meson Coupling ◽  
Resonance Coupling

In the context of a relativistic mean field theory the delta-resonance matter formation in a highly compressed nuclear medium is investigated. For a given set of nucleon–meson coupling constants, the delta-resonance formation is studied by changing the delta-meson coupling constants. The effect on the equation of state and on the delta-resonance population with respect to changes in the delta-resonance coupling constants values is discussed for very asymmetric and quasi-symmetric nuclear matter, as an extension of works restricted to the symmetric nuclear matter treatment.5,6

scholarly journals SYMMETRIC GROUND STATES FOR A STATIONARY RELATIVISTIC MEAN-FIELD MODEL FOR NUCLEONS IN THE NON-RELATIVISTIC LIMIT

2012 ◽  
Vol 24 (10) ◽  
pp. 1250025 ◽  
Author(s):  
MARIA J. ESTEBAN ◽  
SIMONA ROTA NODARI
Keyword(s):  
Nuclear Physics ◽  
Field Model ◽  
Mean Field ◽  
Ground States ◽  
Good Choice ◽  
Coupling Constants ◽  
Mean Field Model ◽  
Relativistic Limit ◽  
Relativistic Mean Field ◽  
The One

In this paper, we consider a model for a nucleon interacting with the ω and σ mesons in the atomic nucleus. The model is relativistic, but we study it in the nuclear physics non-relativistic limit, which is of a very different nature from the one of the atomic physics. Ground states with a given angular momentum are shown to exist for a large class of values for the coupling constants and the mesons' masses. Moreover, we show that, for a good choice of parameters, the very striking shapes of mesonic densities inside and outside the nucleus are well described by the solutions of our model.

Sign in / Sign up

Export Citation Format

Share Document